Swimming pool construction and adjunct



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Jan. 13, 1970 J. BILLIG ET AL 3,488,782

SWIMMING POOL CONSTRUCTION AND ADJUNCT Filed July 3l, 1969 2Sheets-Sheet 2 United States Patent O 3,488,782 SWIMMING POOLCONSTRUCTION AND ADJUNCT Jules Billig and Clemens Resseguier, New York,N.Y.,

assignors to Bilnor Corp., Brooklyn, N.Y., a corporation of New YorkF-iled July 31, 1969, Ser. No. 846,369 Int. Cl. E04h 3/16 U.S. Cl. 4-17233 Claims ABSTRACT OF THE DISCLOSURE The invention contemplates aswimming pool of the variety in which a compliant plastic liner, such asof polyvinyl film or sheet material, defines the water-confining part ofthe pool cavity. The plastic liner comprises side and bottom panels, toone or both of which compliant plastic envelope is secured andeffectively united. Valving means incorporated in the envelope enablesthe envelope to be amply filled with pool water, at the time the pool isitself filled. When the pool is filled the envelope is self-retainingwith the desired contouring. Various contouring and valving arrangemntsare disclosed.

BACKGROUND OF THE INVENTION- GENERAL FIELD This invention relates to animproved swimming-pool construction, particularly pools in which a layerof pliable plastic, water tight sheet material lines the bottom andIgenerally the side-wall portions of the pool.

Pools of the character indicated are intended primarily for the sa-feenjoyment of water enthusiasts. Because the water level is relativelyshallow, as from one to four feet deep, the bottom is fiat, and the areafor swimming is restricted, a challenge is presented, to provideenhanced enjoyment of the pool, through increased variety of usesthereof.

It is an object of the invention to provide a pool construction of thecharacter indicated wherein increased utility and enjoyment areavailable from variously characterized bottom and/or side contouringformations of compliant material.

Another object is to provide contour formations of the characterindicated as integral parts of the pool liner.

A specific object is to meet the above objects with formations integralwith the pool liner and capable of simple erection during the filling ofthe pool. A further specific object is to provide formations integralwith the pool liner, inherently self-filling or erecting during thefilling of the pool.

Another specific object is to achieve the foregoing without requiringspecial earth excavation or erection of solid matter in order to retaindesired contouring.

A general object is to achieve the foregoing objects with constructionsof elemental simplicity, ruggedness, and low cost, lending themselves tofool-proof erection by the householder of the most modest mechanicaltalent.

Other objects and various further features of novelty and invention willbe pointed out or will occur to those skilled in the art from a readingof the following specification in conjunction with the accompanyingdrawings. In said drawings, which show, for illustrative purposes only,preferred forms of the invention:

FIGULRE 1 is a perspective view of a swimming pool incorporating acentral island formation in accordance with the invention;

FIGURE 2 is a simplified schematic cross-sectional view through theisland part of FIGURE 1;

3,488,782 Patented Jan. 13, 1970 ICC FIGURE 3 is a simplified enlargedfragmentary sectional view to illustrate Valving of FIGURE 2;

FIGURE 3A is a view similar to FIGURE 3 to illustrate modified Valving;

FIGURE 4 is a view similar to FIGURE 2 to illustrate a modification;

FIGURE 4A is a fragmentary sectional view to show a modification ofFIGURE 4;

FIGURES 5 and 6 are views similar to FIGURE 4 to illustrate otherembodiments;

FIGURES 7, 8 and 9 are fragmentary sectional views through lstillfurther embodiments in which the contouring is achieved in conjunctionwith both bottom and sidewall portions of the pool liner;

FIGURE l0 is a fragmentary perspective view of another embodiment; and

FIGURES 1l and 11A are similar fragmentary sectional views to illustratephysical relationships for further valve embodiments.

Briefly stated the invention contemplates a swimming pool of the varietyin which a compliant plastic liner, as of polyvinyl film or sheetmaterial, defines the waterconfining part of the pool cavity. Theplastic liner comprises side and bottom panels, to one or both of whichan inflatable compliant plastic envelope is secured and effectivelyunited. Valving means incorporated in the envelope enables the envelopeto be amply filled, with pool water, at the time the pool is filled. Andwhen the pool is filled, the envelope is self-retaining with the desiredcontouring. Various contouring and Valving arrangements are disclosed.Throughout the specification and claims the words filled, infiated,water-filled and water inflated lare used. These are intended tointerchangeably define the desired condition within the envelope whichmay be all water, or water and air at various pressures.

Referring to FIGURE l, the invention is shown in application to aconventional swimming pool construction of generally circular orcylindrical shape. In accordance with practice, such a pool relies upona rigid, easily erected frame, involving upper and lower frame rings10-11, spaced vertically by plural struts 12. A stiffening shell 13,which may incude vertical corrugations, is contained by the frameworks10-11-12, and a bag 15 of tough compliant plastic, such as l0 to 20gauge polyvinyl (depending upon pool capacity) is suspended from ring 10and serves as the deterrent to water seepage defining a water peripherywhich hugs the shell 13 and the ground at the bottom. When the pool isfilled with water, as suggested in FIGURE l to the level 16, the waterpressure on the sides and bottom causes the liner 15 to smoothly conformto the described backing structure and ground contour,

which is fiat and horizontal, in conventional installations.

In accordance with the invention, variously contoured bottom and sideformations for conventional pools of the character indicated areprovided by employing a compliant infiatable envelope as part of thebottom or side of the liner 15, such envelope being of a material suchas polyvinyl readily securable, as by heat-sealing, to the material ofliner 15. In the form illustrated by FIGURES l and 2, such an envelopedefines an island or hassock 17 at the center of the pool.

The basic shape of the envelope of island 17 may be of generallyprismatic formation, defined by an opstanding body wall portion 20 whichmay be cyindrical or polygonal; the body wall portion 20 extends betweenan upper end 21 which is closed and a lower end which is open, therebydefining an envelope cavity open at the lower end. The lower end of body20 is outwardly flanged at 22 and there secured to a limited area of thebottom panel 15, as by a peripherally continuous heat seal or weld. Toillustrate Valving principles, the envelope of FIGURE 2 is schematicallyshown with three valves 23-24425, the first two of which govern flowthrough the body 20, and the last of which functions at the top of thebowed end 21. Valve 23 is a check valve functioning t0 control one-wayhydraulic flow in the direction to fill the envelope. Valve 24 is athrottle valve for selective discharge of the envelope, as when emptyingthe pool. And valve 25 is an air valve functioning to determine thequality of residual air trapped or introduced in the otherwisewater-filled envelope. It will of course be understood that theindicated valves may be of elemental simplicity, preferably all-plasticand flush mounted to the envelope walls 20-21.

In a typical shipment of the liner 15, with envelope 17 sealed thereto,there is of course next to no air in the envelope, which is in collapsedand folded condition, in a manner best suited to compact packingrequirements. At the pool site, liner 15 is frame-mounted in thecustomary manner, with the envelope 17 lying (collapsed) on the uppersurface of liner 15. A small quantity of air is then introduced into theenvelope, as by blowing or pumping action at valve 23. This smallquantity need in no sense ll the envelope, and will be seen merely as ameans of assuring buoyant lift of the top end 21 as the pool is filled.As the pool water-level rises, water will be admitted freely into theenvelope via check valve 23, and when the pool level 16 is achieved, thewater level in envelope 17 will be slightly lower, being determined bythe compression pressure of trapped air at end 21. In FIGURE 1, thiscondition is seen to cause a small island 17 to be exposed above thewater level.

As will be later described, while the use of air is quite helpful it isby no means necessary either for filling or in the ultimate structureand it is possible to fill the envelope using positive pressure at thevalve.

In use, the island or hassock 17 is firmly positioned and is slightlylocally yieldable below the water level. However, above water level ithas a softer, more compliant texture, consistent with the gauge andnature of the envelope material and with the volume and pressure oftrapped air. In either event, the safety inherent in such compliancewill be apparent.

To drain the pool, conventional techniques are employed, except thatthrottle valve is opened to permit drainage and collapse of the envelope17, as the pool level goes down. Preferably, the relief valve 25includes provision for selective release yof all trapped air before thepool is drained, thus assuring that drainage of water will completelycollapse the envelope 17.

FIGURES 3 and 3A illustrates alternative flushmounted valvingstructures. FIGURE 3 shows a check valve having a molded-plastic body 30having a peripheral ange 31 sealed to the side or body wall 20 of theenvelope, at an opening 32 therein. Valve body 30 has an inlet port oropening 33, and an outlet opening or openings 34, at opposite sides ofthe valve chamber 35. A valve member 36 is positioned by aflexible-tongue connection 37 in register with the inlet 33, which alsoserves as the checkvalve seat. Tongue connection 37 is anchored in thematerial of body 30 and is preferably self-biased for normal lightlyresilient urging of the valve-closed position.

The described valve of FIGURE 3 will be seen to provide all thefunctions required of the schematically shown values 23-24 in FIGURE 2.During the pool-filling phase, the valve of FIGURE 3 freely admits waterwithin the envelope lbody 20, and when emptying the pool one need onlyfinger-depress or jam the valve member 36 in its unseated position, toallow full water drainage.

In the valving means of FIGURE 3A, the body 40 is essentially afiush-mounted eye or grommet defining a restrictive orifice 41 which inone form allows water to bleed, i.e. to fiow at a restricted rate, fromone to the other side of body wall 20. If the orifice 41 is of largeproportions, the valving means of FIGURE 3A is shown to include anexternally accessible plug element 42, pref- 4 erably flexibly hinged tothe -body 40 by an integral strap connection 43. A concave groove ornecked-down portion 44 between the axial limits of plug 42 will beunderstood to have detent-retaining coaction with orifice 41 when invalve-closed position.

FIGURE 4 illustrates a modified hassock or islandtype envelope whereinthe trapped air relied upon to buoy the upper end 45 is provided by afoamed-plastic element 46. If the outer surface of element 46 iscompletely sealed against water absorption, then element 46 may bedirectly secured to the top or bottom surface of the end 45. However, inthe form shown, a further panel 47 of pliable plastic such as polyvinyl,defines with end 45 a pocket for the retention of member 46, beingheatsealed or otherwise bonded at flange 48 to the `upper end of thebody wall 49. As will be appreciated `by those skilled in the art theuse of certain closed cell foams will, in conjunction with conventionalsealing techniques, permit the elimination of one or both polyvinylelements 46 and 47. The single valve 50, which may be as described inFIGURE 3 will fully serve the inflation, orientation, and deflation ofthe envelope of FIGURE 4, it being noted that the structure of FIGURE 4avoids any need to introduce air into the envelope. Preferably, however,two valves will be provided since the ability to clean- Water Hush ishighly desirable; for simplicity, however, generally one-valveapplications have been discussed.

In FIGURE 4A, we illustrate the employment of airmattress techniques toprovide buoyant support of the upper end 45 of the envelope. As shown, acorrugated member 52 is so sealed to one of the surfaces of end 4S as todefine a plurality of air pockets 52', distributed over the area of end45.

FIGURE 5 illustrates that the trapped air beneath the upper end 53 ofthe envelope 54 need not be confined to the entire effective area of end53. An annulus 55 of airfilled material, such as foamed plastic, issized to support merely the peripheral edge portion of upper end 53,being retained in place by a conically shaped pliable member, as ofpolyvinyl sheet, having sealed flange connections to the upper and bodyparts of envelope 54, as will be understood. FIGURE 5 also illustratesthat, when in inated position, the upper end 53 may be below pool waterlevel 16, for the pleasurable use of the submerged pedestal 54 which isthereby established.

In the arrangement of FIGURE 6, the envelope 60 is specially contouredat its yupper end, by a central recess or pocket 61, so that theuppermost part of the end is on Vannulus 62. The annulus is selfsupporting as before depending upon the equalization of water pressureand the natural tendency of the body to assume its preoriented formedshape. If desired, air may `be introduced through valve 25 (not shown inthis figure) or an annulus of foamed material 63 may be provided at thetop for rigidity. The annulus 62 provides a convenient seating region,from which feet may be dangled, without support from the radially outeredge, or with the support of recess 61 if the feet are placed radiallyinwardly of seat 62. A hydraulic connection 64 connects the recess 61 toa submerged part of the envelope body, in order that a free-floodedwading pool may be available within recess 61. Infiation and defiation,using valve 50, is as previously described. Alternatively, theconnection may be eliminated and water provided the interior recess bydepressing any portion of the annulus.

FIGURE 7 illustrates a modification wherein the envelope 65 is sotruncated that the peripheral edge of its cavity may be sealed toadjacent localized regions of both the side panel 66 and the bottompanel 67 of liner 15. Valve 50 again serves for automatic inflation asthe pool is filled, and the provision of foamed material 68 at theoutside corner of the envelope 65 assures both requisite buoyancy and amore yieldable or safety edge 69. The water shading suggests that asubmerged seat, below Water level is afforded by the inflated structureof FIGURE 7.

IN FIGURE 8, the envelope 70 is a substantially flat sheet havingsealed-fiange engagement to bottom and side panels 66-67 of the pool,along a sloping alignment, such that a collapsible ramp bottom isdefined for the otherwise flat bottom of the pool. The phantom outline71 suggests an air-filled slab, mattress, or foamed-plastic supportingelement beneath ramp envelope 70. A che-ck valve 50 and a pluggedorifice valve 40, as described for FIGURES 3 and 3A, respectively, arepreferably carried at lower and upper parts of the ramp envelope, tofacilitate Water-filling and drainage, las Will be understood.

FIGURES 9 and 10 illustrate embodiments of the invention wherein theenvelope (73-74, respectively) is contoured as a set of stairs, which inFIGURE 9 ascend in the direction perpendicular to the adjacent part ofthe side wall 75 of the pool Wall, and which in FIGURE 10 ascend in thedirection parallel to the adjacent part of the side wall 75. In eitherevent, the envelope (73` or 74) may be generally prismatic, and openonly at the bottom end, being sealed only to the bottom panel of linerin the manner already described for other embodiments. However, inFIGURES 9 and l0 the prismatic envelope shapes are truncated on both thebottom end and on one side, to illustrate that the side wall 75 of theliner 15 may serve at least in part to complete the sealed envelope. Aspreviously indicated, flanged edges of the truncation are used to makethe sealed connections, as at 76 to Wall 75 in FIGURE 9, and at 77 towall 75 in FIGURE l0. Since sealing to side wall does increase thepossibility of rupture during use the elimination of this may bedesirable in some cases, whereupon an upstanding panel would of coursebe added. Phantom outlines 78-79 respectively indicate air-filled treadreinforcements for the stair treads, these treads being located by meanspreviously described. Preferably, for stiffness, tread reinforcements78-79 are of cut marine plywood, sealed by a continuous coat of plasticmaterial, further coated with an air-foamed layer, and then furthersealed `by a continuous coat of pliant material such as polyvinyl,readily bondable to the material of the envelope involved (73 or 74) theair-foamed layer will be understood to assure against injury to theenvelope material or to others, by providing relatively soft yieldingtexture at the treads.

FIGURE ll is a simplified fragmentary diagram to illustrate theprinciple of self-inflation of envelope 80, using for illustration but asingle valve orifice which may be of the type described at 40. Valve 40is located near the top of envelope 80, and assuming that envelope 80 isin collapsed condition, it should lirst be grasped and lifted, withvalve 40 to open, to permit a quantity of air to be induced therein. Thepool is then filled and as the Water rises there will at the same timebe some iloW through valve 40 to fill the envelope. As the pool becomesalmost full, the air trapped above valve 40 will have assured buoyanterection of the envelope 80, and the time will come when pool leveleclipses the valve opening; this event is schematically designated 81.The pool filling continues to the final level 16, thereby establishing ahydraulic head D1 above Water level 82 within envelope 80. The level 82is above the level S1, to the extent that the hydraulic head D1 hasachieved equilibrium with the conipressed air trapped above level 82. Ifthe orifice 40 is left open, the envelope 80 remains self-restoring tothe same elevated position, even if a bather has expelled envelope waterat 46, due to sitting on the island; on the other hand, it may bedesired to plug orifice 40 (as described in FIGURE 3A) to assuremaintenance of the island shape, once self-inflated.

Stated differently it is possible once equilibrium has been achieved topermit passage of Water from within to without the envelope and visaversa to relieve pressure surges.

FIGURE llA is in all respects the same as FIGURE l1, except that thecheck valve 50 has been used in place of the orifice valve 40. Fillingcriteria and hydraulic-head considerations remains the same. The onlydifference is that the use of the check valve 50l obviates any need toplug the valve opening. Accordingly, similar reference notation isemployed in FIGURE 11A.

Thus far, the invention has been described in the context ofself-filling constructions, being predicated on the proposition thatinherent buoyancy in an upper part of the envelope, whether in foamedplastic, air cells, or as merely an entrapped upper region of air, willalways so raise the structure as to induce Water-filling through a checkvalve, as at 50. It will, of course, be apparent that for this result tobe achieved, the water level inside the envelope must necessarily bebelow that of the pool, at 16.

On the other hand, it may be desired for one or more of the describedenvelopes to be water-filled to pool level or above, and in suchinstances the nature of inlet 33 to valve 50 (FIGURE 3), or that at 41to valve 40 (FIG- URE 3A), will be seen to afford ready forced inductionof water, as by merely holding a garden-hose to the valve inlet. In atypical operation of this kind, which, incidentally, represents thepreferred utilization of the invention, as for example of the FIGURE 2variety, a small quantity of air is first introduced into the envelope,the pool is then filled to just below its ultimate level, at which timethe trapped air in the envelope will have raised or piloted the envelopeto a partially extended but correct orientation. Water is then forced byhose pressure at the inlet check valve to fill the envelope, and ifdesired, the trapped air is vented at relief valve 25 to assure completeWaterfilling. The pool is then filled to capacity, i.e. to level 16,which may be somewhat lower than the Water-filled upper end of theenvelope.

The described pressure-filling technique will be seen as applicable toall described envelope configurations, except that if the wading-poolembodiment of FIGURE 6 is to be used with the annular seat or rim 62supported by a water column extending above the pool level 16,precautions must be taken to assure against blow-out of the wading-poolbasin on recess 6l. FIGURE 6A illustrates that blow-out protection isachieved by a stiffening basin member 61' sealed to and thereforeforming part of the envelope 60, as by a peripheral seal of member 61 toa suitably cut-out central part of the upper end of envelope 60. In theform shown, the stiffening basin member 61 is integrally formed with aflange 62 to define upper end of the envelope as a more stitiiy rigidbody. The upstanding pliant side Wall 60 of the envelope is thus sealedto the outer edge of the basin member 61. The latter may be a singleinjection-molded piece of suitable plastic, such as polyvinyl, and theside Wall.60' may be of sheet polyvinyl stock, cut to length appropriateto the circumferential extent of Wall 60', and heat sealed on avertically seamed connection (not shown) of the cut ends of the lengthof sheet material. Since liotation 63 is unnecessary to the waterpressure-filled form of FIGURE 6A, it is not shown, although it may beprovided for other reasons, such as more comfortable texture or velvetyfeel at the seating surface.

It has been observed that the self-infiating versions of the inventionrely upon slight residual positive buoyancy, for erection andwater-fillings, and that this is not neces- `sary for thewater-pressurized employments, in which retaining force to the entireflange; the section of such a hoop of pipe is suggested by phantomoutline 51 in FIG'- URE 4.

It will be seen that we have described novel pool constructions lendingthemselves to varied applications and uses, for the safe and morepleasurable employment of an otherwise conventional swimming pool.Whether self-infiated, or inflated by garden-hose application, ourstructures are readily erected by the homeowner himself. Moreover, itwill be understood that while the envelope structures have beendescribed as integrally united with the pool liner 15, they may becomplete in and of themselves, as shown by the dashed line 49' in FIGURE4. Thus the lower envelope panel may be virtual (as where it is definedby liner or it may be real. Then the same selfiniiating properties applyfor the envelope 49-45 as long as the base fiange thereof issufficiently well held down as the pool is filled; such holding may beaccomplished by adhesive or snap-fastener action between the envelopeflange and the liner bottom, but the pipe designation 51 suggests thefurther alternative of weighting the envelope flange. Of course, if sucha unitary envelope 49-45 is hose-filled to a water level above the poollevel 16, then movement of large envelopes is limited (or might even insome cases be desirable) in which case fastening the envelope in placecould be eliminated.

Since all of the described shapes, as well as many others as will occurto the reader, may be self-contained (i.e. include a bottom envelopepiece integral with the sides and top) it will be apparent that suchenvelope units may be interchangeable and sold separately to permit agreater choice with less inventory requirements on the dealer.

Regardless of the technique of envelope filling, however, it will beappreciated that the filled envelope does not Iand cannot achieve itsintended function and result without the coaction from surrounding poolwater, i.e. when the pool is filled.

While the invention has been described in detail for the preferred formsshown it will be understood that modifications may be made withoutdeparting from the scope of the invention as dened in the claims whichfollow. For example, the described version of FIGURE 11 wherein theorifice 40 is continuously open suggests a pleasurably useful deviceeven though body weight may slowly collapse the inflated envelope;regardless of the degree of collapse, the stiffness of the basicenvelope shape, or the piloting or positively buoyant effect of trappedair or floatation, will always Iassure shape restoration. Moreover, theabusive local incision of the filled envelope (below pool level) neednot be disastrous, and may provide extended enjoyment, due to theresultive orifice action already described in connection with FIGURE 11.

Since arrangements have been described wherein there is a positivepressure inside the envelope vis-a-vis the pool it may be desirable toadd circumferentially spaced or otherwise placed stress bands ofpolyvinyl or other material to insure shape retention. Where ltheenvelope is to be heat sealed to the pool liner it is suggested that theenvelope be slightly less in thickness than the liner insuring that incase of stress causing rupture the adjunct and not the pool is injured.

Although the specification discusses a number of constructions in all ofwhich the sheet material lines both the bottom and sides, it is to beclearly understood that this invention applies with like import to poolswherein only the bottom liner is so formed, the side being for examplemetal with a water tight seal to the bottom sheet material.

What is claimed is:

1. A swimming pool including la compliant plastic liner at least at thebottom thereof and an upstanding side panel and a fillable compliantplastic envelope secured at least in part to a localized part of theupper surface of said bottom panel, the upper surface of the compliantplastic envelope defining with the liner surrounding said envelope thebottom contour of said pool said envelope including valve meansaccommodating the selective flow of liquid between the inner volume ofsaid envelope and the adjacent volume of said pool.

2. A pool according to claim 1, wherein said envelope is generallyconcave with the concavity open on at least one side, thereby defining aperipheral edge of said envelope, said peripheral edge being secured atleast in part to said bottom panel.

3. A pool according to claim 2, wherein said peripheral edge is alsosecured to a localized part of said upstanding side panel, said sidepanel also being of compliant plastic.

4. A pool according to claim 2, wherein said envelope is of generallyprismatic formation defining an upstanding body wall betweensubstantially parallel spaced ends one of which is open to define theopen concavity.

5. A pool according to claim 1, wherein said envelope comprises a sheetwith a peripheral edge substantially continuously secured to a localizedarea of said bottom panel, said localized area being less than theeffective surface area of said sheet comprehended within the securedregion of said sheet.

6. A pool according to cl-aim 4, wherein said prismatic formation isgenerally right-cylindrical on an upstanding axis.

7. A pool according to claim 6, wherein said pool is generallycylindrical and said prismatic formation is centrally secured to saidbottom panel.

8. A pool yaccording to claim 4, wherein the upper end of said envelopeis centrally recessed to an extent less than the space between saidends, and a hydraulic iiuid connection communicating between therecessed part of the body wall below normal water level in said pool.

9. A pool according to claim 1, in which said valve means includes anair valve which, in the filled condition of said envelope, at elevatedpart of said envelope.

10. A pool according to claim 9, in which said air valve is apressure-relief valve.

11. A pool according to claim 1, in which said valve means is a checkvalve which, in the inflated condition of said envelope, is at anelevation below normal water level in said pool.

12. A pool according to claim 1, in which said valve means comprises twocheck valves one of which, in the filled condition of said envelope, isat an upper elevation of said envelope and the other of which, in thefilled condition of said envelope, is at a lower elevation of saidenvelope.

13. A pool according to claim 12, wherein said check valves areoper-ative to check fiuid flow against egress from said envelope, saidvalve each including selectively operable means to permit opening thesource for egress of fluid, whereby upon filling the pool and with aninitial volume of air in said envelope, said lower check valve may beprimarily responsible for automatic admission 0f pool water within saidenvelope, and upon operation of said selectively operable means of saidupper valve, said upper valve may be caused to discharge to the desiredeX- tent such air as is contained within said envelope; and fur-- therwhereby, upon draining the pool, the selectively operable means of atleast the lower valve may be operative to drain fluid from saidenvelope.

14. A pool according to claim 1, wherein said valve means comprises asingle check valve which, in the filled condition of said envelope, isnear but short of the upper limit of said envelope, said check valvecomprising a valve member admitting hydraulic fiow in the direction fromsaid pool and into said envelope and responsive to hydraulic fiow inopposite direction to check the same, said valve member being furtherineffective to check escaping air flow as water is admitted into saidenvelope, the normal pool-filled level being above the level of saidcheck valve; whereby upon filling the pool, said envelope will fill withwater to a level above said valve until the pressure of envelope-trappedair balances the hydraulic head represented by the extent to which thepool water level exceeds the water level within said envelope.

15. A pool according to claim 1, wherein said valve means includes arestrictive orifice which, in the filled condition of said envelope, isnear but short of the upper limit of said envelope, said orificeproviding locally restricted fluid communication between regions insideand outside said envelope, the normal pool-filled level being above thelevel of said orifice; whereby upon filling the pool said envelope maybe filled with water to a level above the orifice until the pressure ofenvelope-trapped air balances the hydraulic head represented by theextent to which the pool water level exceeds the water level within saidenvelope may be self-draining.

16. A pool according to claim 1, in which the filled condition of saidenvelope, an air-entrapping member is positioned adjacent an upwardlyfacing region of said envelope.

17. A pool according to claim 16, in which said airentrapping member isof foamed material.

18. A pool according to claim 16, in which said airentrapping member islocally secured to said region of said envelope to define an air pocketbetween said member and said envelope region.

19. A pool according to claim 16, in which said airentrapping member islocally secured to said region of said envelope to define plural spacedair pockets of limited individual areas, between said member and saidenvelope region and distributed throughout said region.

20. A pool according to claim 1, wherein said envelope comprises a sheetwhich, in the filled condition of said envelope is substantially fiatand sloped from the horizontal, said sheet being substantiallyperipherally continuously secured in part to said bottom panel and inpart to said side panel, thereby defining a ramp bottom for said pool.

21. A pool according to claim 4, wherein the opening of said concavityis also at a localized part of said up- -standing body wall, saidenvelope being substantially peripherally continuously secured in partto said bottom panel and in part to said side panel, said side panelbeing also of compliant plastic, thereby defining a prismatic formationcontiguous to said bottom and side panels.

22. A pool according to claim 21, wherein said prismatic formation isgenerally rectangularly prismatic, truncated at the locus of securing tosaid panels.

23. A pool according to claim 21 wherein said prismatic formation isgenerally right cylindrically prismatic, truncated at the locus ofsecuring to said panels.

24. A pool according to claim 21, wherein said prismatic formationincluded plural progressively stepped upwardly facing surfaces, andair-entrapping means carried at each of said upwardly facing surfaces.

25. A pool according to claim 24, wherein the direction of steppedprogression is substantially parallel to the local side-panel region towhich said prismatic formation is secured.

26. A pool according to claim 24 wherein the direction of steppedprogression is substantially perpendicular to the local side-panelregion to which said prismatic formation is secured.

27. A pool according to claim 1, wherein a portion of said liner iscommon to said envelope and liner, said portion together with saidenvelope defining a complete, llable enclosure within the pool.

28. In combination, a swimming pool filled to normal water level, and aprismatic bottom-contour characterizing element comprising an envelopeof compliant plastic material having an externally characterized shapewhich in water-inflated condition has an external lowermost contourwhich conforms to the pool bottom and which invelope rest thereon withinthe filled pool defining with the pool bottom surrounding the element anew pool bottom contour, said envelope being water filled at least tosubstantially the normal water level of said pool, the trapped watermass within said envelope and the conforming nature of the pool bottomand lowermost element contour statically maintaining the elementposition in the pool.

29. The combination according to claim 28, in which said envelope iswater filled to a level above normal pool water level, whereby thefilled envelope as a whole is negatively buoyant and is therefore inloaded relation with the pool bottom.

30. The combination of claim 28, in which said envelope is slightlypositively buoyant at an upper part thereof and is negatively buoyant atlower portions thereof.

31. In combination, a swimming pool filled to normal water level, and aprismatic bottom-contour characterizing element comprising an envelopeof compliant plastic material having an externally characterized shapewhich in water-inflated condition has an external lowermost contourwhich conforms to the pool bottom and which envelope rest thereon whichin the filled pool defining with the pool bottom lsurrounding theelement a new pool bottom contour, said envelope being of verticalextent less than the pool depth and totally water-filled, and meanslocating said envelope with respect to a localized part of the bottom ofthe pool.

32. In combination, a swimming pool filled to normal water level, and aprismatic bottom-contour characterizing element comprising an envelopeof compliant plastic material having an externally characterized shapewhich in water-inflated condition has an external lowermost contourwhich conforms to the pool bottom and which envelope rest thereon whichin the filled pool defining with the pool bottom surrounding the elementa new pool bottom contour, said envelope being of vertical extent lessthan the pool depth and totally water-filled, the overall envelopedensity exceeding unity, whereby the waterfilled envelope is negativelybuoyant and therefore locates on the bottom of the pool.

33. The combination of claim 30, in which the overall density of theenvelope, including positively buoyant parts thereof, exceeds unity,whereby the water-filled envelope is negatively buoyant butselforienting in located relation with the bottom of the pool.

References Cited UNITED STATES PATENTS 3,072,922 1/1963 Pyke 4 172153,355,745 12/1967 Jannuzzi 4-172.12 3,366,977 2/1968 Koehler 4-172.12

LAVERNE D. GEIGER, Primary Examiner H. K. ARTIS, Assistant Examiner

